The navigational problems which are solved by the present invention, as well as the invention itself, are applicable to all aircraft, are particularly useful in rotary wing aircraft, and are described as they might be implemented in an unmanned rotary wing aircraft.
Typical navigation may utilize courses established to lead an aircraft from one waypoint (such as a VOR navigation beacon) to the next waypoint. Most aircraft autopilot systems use the course deviation to the next station to adjust yaw through a proportional and integral path. If the aircraft is on course, but the wind is blowing it off course, no corrective action will be taken until there is a sufficient error. Thus, the aircraft will fly in a path more characterized as a saw tooth than in a straight line.
When an aircraft is significantly off-course, its heading can be changed so as to cause it to point directly toward the next waypoint, thereby reaching the next waypoint in the most efficient manner. However, the consequences of flying to the waypoint from a different origin with a different heading may be unknown. For instance, there may be significant obstacles which are best avoided by flying along the originally-planned course. Thus, accuracy in following substantially the originally-planned course may be paramount. Thus, when off-course, it may be necessary to return to the original course and assume the original heading.